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1 /*
2  * Copyright (C) 2013 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #ifndef ANDROID_HWUI_RENDER_BUFFER_CACHE_H
18 #define ANDROID_HWUI_RENDER_BUFFER_CACHE_H
19 
20 #include <GLES2/gl2.h>
21 
22 #include "RenderBuffer.h"
23 
24 #include <set>
25 
26 namespace android {
27 namespace uirenderer {
28 
29 class RenderBufferCache {
30 public:
31     RenderBufferCache();
32     ~RenderBufferCache();
33 
34     /**
35      * Returns a buffer with the exact specified dimensions. If no suitable
36      * buffer can be found, a new one is created and returned. If creating a
37      * new buffer fails, NULL is returned.
38      *
39      * When a buffer is obtained from the cache, it is removed and the total
40      * size of the cache goes down.
41      *
42      * The returned buffer is always allocated and bound
43      * (see RenderBuffer::isAllocated()).
44      *
45      * @param format The desired render buffer format
46      * @param width The desired width of the buffer
47      * @param height The desired height of the buffer
48      */
49     RenderBuffer* get(GLenum format, const uint32_t width, const uint32_t height);
50 
51     /**
52      * Adds the buffer to the cache. The buffer will not be added if there is
53      * not enough space available. Adding a buffer can cause other buffer to
54      * be removed from the cache.
55      *
56      * @param buffer The render buffer to add to the cache
57      *
58      * @return True if the buffer was added, false otherwise.
59      */
60     bool put(RenderBuffer* buffer);
61     /**
62      * Clears the cache. This causes all layers to be deleted.
63      */
64     void clear();
65 
66     /**
67      * Returns the maximum size of the cache in bytes.
68      */
69     uint32_t getMaxSize();
70     /**
71      * Returns the current size of the cache in bytes.
72      */
73     uint32_t getSize();
74 
75 private:
76     struct RenderBufferEntry {
RenderBufferEntryRenderBufferEntry77         RenderBufferEntry():
78             mBuffer(nullptr), mWidth(0), mHeight(0) {
79         }
80 
RenderBufferEntryRenderBufferEntry81         RenderBufferEntry(GLenum format, const uint32_t width, const uint32_t height):
82             mBuffer(nullptr), mFormat(format), mWidth(width), mHeight(height) {
83         }
84 
RenderBufferEntryRenderBufferEntry85         RenderBufferEntry(RenderBuffer* buffer):
86             mBuffer(buffer), mFormat(buffer->getFormat()),
87             mWidth(buffer->getWidth()), mHeight(buffer->getHeight()) {
88         }
89 
90         static int compare(const RenderBufferEntry& lhs, const RenderBufferEntry& rhs);
91 
92         bool operator==(const RenderBufferEntry& other) const {
93             return compare(*this, other) == 0;
94         }
95 
96         bool operator!=(const RenderBufferEntry& other) const {
97             return compare(*this, other) != 0;
98         }
99 
100         bool operator<(const RenderBufferEntry& other) const {
101             return RenderBufferEntry::compare(*this, other) < 0;
102         }
103 
104         RenderBuffer* mBuffer;
105         GLenum mFormat;
106         uint32_t mWidth;
107         uint32_t mHeight;
108     }; // struct RenderBufferEntry
109 
110     void deleteBuffer(RenderBuffer* buffer);
111 
112     std::multiset<RenderBufferEntry> mCache;
113 
114     uint32_t mSize;
115     uint32_t mMaxSize;
116 }; // class RenderBufferCache
117 
118 }; // namespace uirenderer
119 }; // namespace android
120 
121 #endif // ANDROID_HWUI_RENDER_BUFFER_CACHE_H
122